I don't know much about science, I'm just curious about how much warming a certain amount of CH4 would cause compared to a similar amount of CO2 (both 5 GtC). I'm sorry if the question sounded a bit confusing, I'm just a layman trying to learn more about global warming and climate change.
In theory, the methane emissions would warm the earth about 25 times more than the carbon dioxide emissions.
That's because of something called the global warming potential. The global warming potential of a greenhouse gas is how much it warms the planet compared to carbon dioxide's base value of 1. As you might expect, methane's GWP is 25.
Figure 3a of Evaluating Climate Emulation: Fundamental Impulse Testing of Simple Climate Models compares the temperature response of pulses of CO2 and HC4 (I can't see where they specify the relative quantities).